1. Field of the Invention
The present invention relates to a method for controlling a refrigerator, and more particularly, to a method for preventing formation of ice on a damper in a refrigerator, which damper is provided in a cooled air flow passage for selective supply of the cooled air to a chilling chamber.
2. Background of the Related Art
The refrigerator is an appliance which maintains food stored in the refrigerator at a required temperature using a refrigerating cycle of a refrigerant having compression, condensation, expansion, and evaporation. The refrigerator including a freezing room and a chilling room is provided with a refrigerator body and different components fitted to various positions of the body for conducting the refrigerating cycle. The components for conducting the refrigerating cycle are a compressor, an evaporator, an expansion valve, a condenser, a fan, and etc. The evaporator is provided in a heat exchange chamber in rear of the freezing chamber, wherein the refrigerant makes heat exchange with ambient air and is evaporated into gaseous refrigerant, while cooling down the ambient air. The air cooled down at the heat exchange with the refrigerant at the evaporator is blown by a fan, to flow toward, one portion to the freezing room and the other portion to the chilling room, of which flow of the cooled air toward the chilling room is adjusted by the damper. The cooled down air supplied to the freezing room and the chilling room thus is turned into air of relatively high temperature through heat exchange with the food stored therein, and circulates therefrom through the evaporator, again.
FIG. 1 illustrates a front view of a related art refrigerator, FIG. 2 illustrates a section across a line I--I in FIG. 1, referring to which a related art refrigerator and a damper in the refrigerator will be explained.
Inside of the refrigerator 1 is divided by a barrier 30 having insulator stuffed therein into a freeze room 3 and a chilling room 4, and there is a heat exchange chamber 10 on a rear wall of the freeze room 3, and the heat exchange chamber 10 is provided with an evaporator 10a. There is a cooled air discharge passage 12 formed in the barrier 30 for moving the cooled air heat exchanged in the heat exchange chamber 10 to the chilling room 4, together with return passages 14 and 16 for returning the cooled air circulated through the freeze room 3 and the chilling room 4 respectively back to the heat exchange room 10, again. The return passages 14 and 16 are formed not to be overlapped with the cooled air discharge passage 12. In the meantime, an outlet of the cooled air discharge passage 12 is connected to the cooled air flow passage 36, and there is a damper 20 fitted to an outlet of the cooled air flow passage 36 for controlling cooled air flow into the chilling room 4, and there is a plurality of cooled air discharge openings 32 and 34 for discharging the cooled air into the chilling room 4. And, there are temperature sensors 9 and 11 at left and right inside walls or a rear inside wall of the chilling room 4 for sensing temperatures of the chilling room. The damper 20 is provided with baffles 22 and 22a for selective shut off of the cooled air flow passage 36 and plate springs 24 and 24a for supporting the baffles 22 and 22a respectively, wherein the baffles 22 and 22a are controlled mechanically or electrically based on the temperatures measured at the chilling room temperature sensors 9 and 11. The damper 20 may be provided with on baffle even though the damper 20 shown in FIG. 1 is provided with two baffles 22 and 22a. As shown in FIG. 1, if there are two baffles 22 and 22a provided to the damper, one baffle(a first baffle) 22 is adapted to shut off the cooled air flow passage 36 connected to the cooled air opening 32 which discharges cooled air into a middle compartment 5 of the chilling room 4 selectively, and the other baffle(a second baffle) 22a is adapted to shut off the cooled air flow passage 36 connected to the cooled air opening 34 which discharges cooled air into a low compartment 7 of the chilling room 4, selectively. In this instance, the middle compartment and the low compartment 32 and 34 are of course formed separately and individually, with temperature sensors 9 and 11 at the middle and low compartments 5 and 7 respectively, for respective control of the two baffles 22 and 22a.
A method for controlling the related art refrigerator will be explained with reference to FIGS. 1.about.3.
The method for controlling the related art refrigerator starts with comparing a freezing room temperature Tf measured by a freezing room temperature sensor(not shown) to a freezing room reference temperature Tf.ref for determining drive of the refrigerator 1(S1). If the freezing room temperature Tf is higher than the freezing room reference temperature Tf.ref as a result of the comparison, the refrigerator is put into operation. That is, the compressor and the fan(not shown) are operated for making the refrigerating cycle(S3). If the chilling room temperature Tc does not satisfy the chilling room reference temperature Tc.ref, the baffles 22 and 22a are opened to supply the cooled air to the chilling room 4(S5 and S7). Accordingly, the cooled air cooled by heat exchange at the evaporator is supplied to the freeze room 3 and the chilling room 4. Then, the chilling room temperature Tc is compared to the chilling room reference temperature Tc.ref again(S9), to close the baffles 22 and 22a (S10) for preventing an excessive cooling down of the chilling room if the chilling room temperature Tc is below the chilling room reference temperature Tc.ref. Next, the freezing room temperature Tf is compared to the freezing room reference temperature Tf.ref, to stop the drive of the refrigerator if the freezing room temperature Tf is lower than the freezing room reference temperature Tf.ref. That is, operation of the compressor and the fan are stopped(S13 and S15). Under this state, if the freezing room temperature Tf is higher than the freezing room reference temperature Tf.ref, the compressor and fan are operated again, to drive the refrigerator(S1 and S3). The refrigerator is operative repeating the foregoing process, wherein the freeze room reference temperature Tf.ref is -18.degree. C. and the chilling room reference temperature Tc.ref is 3.degree. C.
In the meantime, if an outside temperature Tout of the refrigerator is low(about 10.degree. C.), an operation factor of the refrigerator drops below 20% as there is substantially no heat exchange in the freezing room because a temperature difference between inside and outside of the refrigerator is not great with a consequential low frequency of operation of the chilling room. And, since a temperature difference between the chilling room temperature Tc and the outside temperature Tout is not so great, the baffles 22 and 22a are almost not opened, putting inside of the chilling room into a state of no cooled air circulation.
The related art refrigerator has the following problems when the refrigerator is used in a comparatively low outside temperature Tout.
When the compressor and the fan are driven while the baffles 22 and 22a are opened, there is no problem of ice formation on the damper 20 as the cooled air circulates inside of the chilling room 4. However, when food with high temperature and high humidity is introduced into the chilling room or when an external air with high temperature and high humidity is introduced into the chilling room by open/closing of the chilling room door under a state the baffles are closed and the compressor and the fan are stopped as the freezing room temperature Tf and the chilling room temperature Tc respectively satisfy the freezing room reference temperature Tf.ref and the chilling room reference temperature Tc.ref, moisture adheres on surfaces of the baffles 22 and 22a or on the cooled air flow passage 36 around the baffles 22 and 22a, to form water drops, which are grown into ice. This is because surface temperatures of the baffles are kept relatively lower than the chilling room temperature Tc as the cooled air does not flows into the chilling room 4, but is stationary around the baffles 22 and 22a when the baffles 22 and 22a are closed as the chilling room temperature satisfies the temperature condition. Accordingly, the air with high temperature and high humidity introduced from outside of the refrigerator or the air evaporated from the food with high temperature and high humidity adheres on surfaces of the baffles 22 and 22a of the damper 20, forming ice on the baffles 22 and 22a. Moreover, the almost no circulation of air in the chilling room 4 as the baffles 22 and 22a are closed enhances the ice formation on the surfaces of the baffles 22 and 22a which have relative low temperatures. As has been explained, this ice formation becomes more serious when the refrigerator is in a cold region, i.e., when the operation factor of the refrigerator is low, because there is scarce air circulation in the chilling room in the refrigerator. Once ice is formed on the damper 20, open/closing of the baffles 22 and 22a can not be made properly according to a temperature in the chilling room 4, resulting in failing of a proper control of cooled air discharge into the chilling room. The failure of a proper control of cooled air discharge into the chilling room causes an excessive drop of the chilling room temperature Tc below the chilling room reference temperature Tc.ref, cooling down the food excessively, that degrades the food and increases a power consumption.
In order to solve such problems, a method for melting the ice on the baffles 22 and 22a has been suggested. However, the method has problems in that a production cost of the refrigerator becomes high and a structure of the refrigerator is complicated because a heater should be provided.